refactor: extract isDarkMode/getColorPrefix to settings.js as shared utilities

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/settings.js

@@ -18,6 +18,10 @@
     "dark.commentsTextColor": "#cccccc",
     subredditColors: {},
     colorPresets: [],
+    badgeLayout: true,
+    cardLayout: true,
+    cardBackground: "reddit",
+    cardGap: 16,
   };
 
   function migrateSubredditColors(colors) {
@@ -60,9 +64,21 @@
     await browser.storage.local.clear();
   }
 
+  function isDarkMode(settings) {
+    if (settings.darkMode === "light") return false;
+    if (settings.darkMode === "dark") return true;
+    return document.body.classList.contains("res-nightmode");
+  }
+
+  function getColorPrefix(settings) {
+    return isDarkMode(settings) ? "dark" : "light";
+  }
+
   window.RedditTweaks = window.RedditTweaks || {};
   window.RedditTweaks.DEFAULTS = DEFAULTS;
   window.RedditTweaks.loadSettings = loadSettings;
   window.RedditTweaks.saveSettings = saveSettings;
   window.RedditTweaks.resetSettings = resetSettings;
+  window.RedditTweaks.isDarkMode = isDarkMode;
+  window.RedditTweaks.getColorPrefix = getColorPrefix;
 })();